Gas turbine combustor basket cooling

ABSTRACT

A step-liner type combustion chamber for a gas turbine has a combustor basket cooling arrangement as part of the combustion air orifice structure. The combustion air orifices include a flanged tubular arrangement for ducting combustion air into the combustion chamber while causing air adjacent to the orifice to flow along the combustor basket wall for cooling purposes. The flange is disposed outwardly of the combustor basket and has a spacer member disposed between the flange and the gasket. The tubular portion extends into the basket. The spacer has a gap disposed on its downstream side. An arrangement for air supply orifices is similar, whereby a disc is raised radially outwardly from the combustor basket surface by a spacer member. Each spacer member has a gap across its downstream side to cause air to flow therethrough between the basket wall and the disc member or flange portion on the tubular arrangements, permitting air currents to pass close to the combustor basket wall. This flow of air next to the basket wall increases heat transfer by convection thereby reducing distortion and weld failure in the combustor basket wall.

United States Patent [191 Parker [4 1 Aug. 19, 1975 GAS TURBINE COMBUSTOR BASKET COOLING [75] Inventor: Stephen R. Parker, Media, Pa.

[73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

221 Filed: Mar. 27, 1974 [21] Appl.No.: 455,161

Primary ExaminerC. .l. Husar Assistant Examiner-Thomas 1. Ross Attorney, Agent, or Firm-G. H. Telfer [57] ABSTRACT A step-liner type combustion chamber for a gas turbine has a combustor basket cooling arrangement as part of the combustion air orifice structure. The combustion air orifices include a flanged tubular arrangement for ducting combustion air into the combustion chamber while causing air adjacent to the orifice to flow along the combustor basket wall for cooling purposes. The flange is disposed outwardly of the combustor basket and has a spacer member disposed between the flange and the gasket. The tubular portion extends into the basket. The spacer has a gap disposed on its downstream side. An arrangement for air supply orifices is similar, whereby a disc is raised radially outwardly from the combustor basket surface by a spacer member. Each spacer member has a gap across its downstream side to cause air to flow therethrough between the basket wall and the disc member or flange portion on the tubular arrangements, permitting air currents to pass close to the combustor basket wall. This flow of air next to the basket wall increases heat transfer by convection thereby reducing distortion and weld failure in the combustor basket wall.

5 Claims, 6 Drawing Figures PATENTED AUG-1 9 I975 SHEET 1 BF 3 GAS TURBINE COMBUSTOR BASKET COOLING BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to combustion chambers for gas turbines, and more particularly to a combustor basket cooling arrangement disposed within the combustor basket air inlet structure.

2. Prior Art In gas turbines, the higher the temperature of the combustion chamber walls during normal operation, the more subject the chambers are to thermal stress and strain. This requires constant maintenance programs whereby combustion chambers must be periodically inspected to insure their operating reliabilities. More recently, because of the advent of larger gas turbine power plants, it has become desirable to operate the plants at higher and higher temperatures. Furthermore, because of the economy involved, it is most desirable to burn heavy residual fuels, which are high in contaminants, rather than the purer fuels such as No. 2 distillate fuel. However, residual fuels radiate substantially more heat to the combustor walls, so that the combustor life and reliability is substantially reduced.

One solution to enable combustion chambers to operate at higher temperatures is the refractory or ceramic combustion chamber. But as of now, the high velocities and violent pulsations in the combustion chambers have prevented the use of refractories in combustors in commercial applications. Another solution is to increase the volume of cooling air to the combustor walls. However, this has an adverse effect on the temperature distribution pattern of the gases when they are introduced to the turbine blades since there is a large temperature differential between the blade tips where the cooler air is, and the blade centers, causing serious thermal stress and strain without the blades.

It would be desirable, then, to design a combustion chamber which would operate at higher temperatures for extended periods of time, or in the alternative operate at cooler temperatures than the present combustors operating at normal conditions, so that it would be subjected to fewer thermal stresses and strains than pres ent combustors. This in turn would require less periodic inspections since its reliability would be substantially increased. It would be desirable to design a combustor that would be economical to construct and easy to assemble.

SUMMARY OF THE INVENTION A gas turbine power plant has a compressor section, in which there is disposed at least one combustor or combustion chamber, and a turbine section. The combustion chamber is of the step-liner type and is comprised of wall portions having a step configuration, each of the portions being of greater diameter than the preceding portion from the upstream end to the downstream end of the combustor. Disposed in annular arrays within the liner portions are several types of combustion air inlet orifices. One type of combustion air inlet orifice is comprised ofa generally tubular member extending inwardly into the combustor basket through a hole in the wall of the combustor. The tubular member has an annular flange on its radially outer end. An intermediate spacer is fixedly attached around each hole, to the combustor basket, and the flange is attached radially outwardly of the spacer. The spacer has an arcuate gap on its downstream side to permit air to flow between the flange and the wall of the combustor basket. The air flowing next to the combustor basket wall aids in convective heat transfer with the hot combustor basket walls. This air also prevents combustion flame from attaching to the downstream side of the tubular portion of the air inlet orifice, reducing the incidence of inlet orifice burning common in the prior art.

A similar type combustor basket wall cooling arrangement is used for combustion air holes, wherein a disc member having a hole therein is disposed over an intermediate spacer having a hole. The spacer being disposed about an air entrance hole in the combustor basket wall. An arcuate gap is disposed on the downstream side of the spacer member to permit air to flow between the disc member and the wall of the combustor basket.

The air passing adjacent to the combustor basket wall due to the above described configuration increases the convective heat transfer from the conbustor wall and therefore reduces distortion and spot weld failures common to the prior art. The air entering the combustor basket close to the main entrance passageway reduces the entrainment of any cooling film caused by the ejector effect of the air jet entering into the combustor basket through the main air entrance passageways.

BRIEF DESCRIPTION OF THE DRAWINGS The invention, along with the objects and advantages thereof will be best understood from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is an axial sectional view of a portion of the upper half of a gas turbine power plant provided with combustion apparatus constructed in accordance with the principles of this invention;

FIG. 2 is an enlarged sectional view of the combus tion apparatus illustrated in FIG. 1;

FIG. 3 is a view taken along lines III-III of FIG. 2;

FIG. 4 is a view taken along lines IV-IV of FIG. 3;

FIG. 5 is a view taken along lines VV of FIG. 2; and,

FIG. 6 is a view taken along lines VIVI of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings in detail and particularly to FIG. I, there is shown a portion of a gas turbine power plant 10 having combustion apparatus 12. However, the combustion apparatus 12 may be employed with any suitable type of gas turbine power plant. The power plant 10 includes an axial flow air compressor 14, for directing air to the combustion apparatus 12, and a gas turbine 16 connected to the combustion apparatus 10, which receives hot products of combustion therefrom for motivating the power plant.

Only the upper half of the power plant and combustion apparatus has been illustrated, since the lower half may be substantially identical and symmetrical about the center line or axis of rotation R R of the power plant.

The air compressor 14, includes, as well known in the art, a multistage bladed rotor structure 18 cooperatively associated with a stator structure having equal number of multistage stationary blades 20 for compressing the air directed therethrough to a suitable pressure value for combustion in the combustion apparatus 12. The outlet of the compressor 14 is directed through an annular diffusion member 22 forming an intake for a plenum chamber 24, partially defined by a housing structure 26. The housing 26 includes a shell member of circular cross section 25, and as shown, of cylindrical shape, coaxial with the axis of rotation R R of the power plant 10, a forward dome-shaped wall member 28 connected to the external casing of the compressor 14 and a rearward annular wall member 30 connected to the outer casing of the turbine I6.

The turbine 16, as mentioned above, is of the axial flow type and includes a plurality of expansion stages formed by a plurality of rows of stationary blades 32 cooperatively associated with an equal plurality of rotating blades 34 mounted on a turbine rotor 36. The turbine rotor 36 is drivingly connected to the compressor rotor by a tubular connecting shaft member 27, and a tubular liner or fairing member 29 is suitably supported in encompassing stationary relation with the connecting shaft portion 27 to provide a smooth air flow surface for the air entering the plenum chamber 24 from the compressor diffuser 22.

Disposed within the housing 26 are a plurality of tubular elongated combustion chambers or combustors 38 only one being shown, of the telescopic step-liner type. The combustion chambers 38 are disposed in an annular mutually spaced array concentric with the center line of the power plant and are equally spaced from each other in the housing 26. The chambers 38 are arranged in such a manner that their axes are substantially parallel to the outer casing 26 and with the center line R R of the power plant 10. It is pointed out that this invention is applicable to other types of combustors such as the single annular basket type or the can annular type having composite features of the canister and annular types.

Since the combustors 38 may be substantially identical, only one will be described. As shown in FIG. 1, each combustor 38 is comprised of three sections: an upstream primary portion 40, an intermediate secondary portion 42 and a downstream transition portion 44.

The forward wall 28 of the combustion apparatus 12 is provided with a central opening 35 through which a fuel injector 37 extends. The fuel injector 37 is supplied with fuel by a suitable conduit 39 connected to any suitable fuel supply, not shown, and may be of the well known atomizing type formed in a manner to provide a substantially conical spray of fuel within the primary portion 40 of the combustion chamber 38. A suitable electrical ignitor 41 is provided for igniting the fuel and air mixture in the combustor 38.

In the primary portion 40 of the combustor 38 are a plurality of liner portions 47 of circular cross section and in the example shown, the liner portions are cylindrical. The primary portion 40 is of stepped liner construction, each of the liner portions 47 having a circular section of greater circumference or diameter than the preceding portions from the upstream to the downstream end of the combustor to permit telescopic insertion of the portions. Some portions 47 have an annular array of apertures, 50 and 52, for admitting primary or secondary air from within the plenum chamber 24 into the primary portion 40 of the combustor to support combustion of the fuel ejected therein by the fuel injector 37. The combustor 38 further includes the intermediate portion 42 which is provided with additional arrays of annular rows of apertures 50 and 52 for admitting secondary air from the plenum chamber 24 into the combustor 38 during operation, to cool the hot gaseous products and make it adaptable to the turbine blades 32 and 34. The transition portion 44 is provided with a forward portion 45 of cylindrical shape disposed in encompassing and slightly overlapping relationship with the intermediate portion 42. The transition protion 44 is also provided with a rearward tubular portion 49 that purposely changes in contour from a circular cross section at the juncture with the cylindrical portion 45 to an arcuate cross section at its outlet end portion 51. The arcuate extent of the outlet 51 is such that jointly with the outlets of the other combustors 38, not shown, a complete annulus is provided for admitting the hot products of combustion from each of the combustors 38 to the blades 32 and 34 of the turbine 16, thereby to provide full peripheral admission of the motivating gasses into the turbine 16.

In accordance with the invention, the combustor 38 has a plurality of combustion air orifices or apertures 50 and 52 disposed in annular arrays thereon. The combustion air orifices, 50 and 52, a partial array being shown in FIG. 2, comprise a portion of the combustion air supply means, which cause air to enter the combustor 38 through a plurality of holes 49 in the combustor liner member 47 or basket walls.

Aperture 50, otherwise known as an air scoop, is shown in detail in FIGS. 3 and 4. The aperture 50 is comprised of a tubular portion 60, a generally annular flange portion 62, and an intermediate spacer member 64. Each tubular portion 60, is disposed through a hole 49 in the basket wall 47, and extends radially inwardly into the combustion chamber of combustor basket 38. Disposed between the walls or liner 47 of the combustor basket 38 and the annular flange member 62 of the air scoop 50 is an intermediate spacer member 64. The intermediate spacer member 64 may be generally C- shaped, however, the gap portion may be larger than the spacer member segment 64 itself. An arcuate gap 66, defined by the dotted lines 65 and 67 is shown in FIG. 3, on the downstream side of the scoop 50. The gap 66 could be defined by dotted lines 65' and 67 or by a plurality of arcuate gaps spaced therebetween. The arcuate gap 66 shown in FIG. 3, permits the flow of air therethrough, cooling the combustor basket wall 47. The air flowing through the arcuate gap follows the path indicated by the letter E, shown in FIG. 4. The tubular portion 60 of the aperture or air scoop 50, forces some of the air into the inner portion of the combustor 12 for combustion of the fuel and the mixing of the combustion products. The air scoop 50 is shown in FIGS. I and 2, on both the primary combustor areas 40 and the secondary diluent areas 42 of the combustor 38.

Aperture 52, described otherwise as an air orifice, is shown in detail in FIGS. 5 and 6. Each aperture 52 is disposed radially outwardly of its respective hole 49 in the liner walls 47 of the combustor basket 38. Each air orifice 52 is comprised of a disc member 70, and a generally C-shaped intermediate spacer member 72. Each disc member 70 has a hole 73 disposed through its center portion. The diameter of the hole 73 in disc 70 may be dissimilar to the diameter of its respective hole 49 that is disposed in the wall 47 of the combustor basket 38. Disposed between the walls or liner 47 of the combustor basket and the disc member 70, is C-shaped intermediate spacer member 72. An arcuate gap 74, defined by the dotted line 75 and 77, is shown in FIG. 5, disposed on the downstream side of the air orifice 52. The gap 74 may be defined by a combination of the dotted lines 75, 75", 77 and 77". The arcuate gap 74 in any case, permits the flow of air therethrough, cooling the combustor basket wall 47, by convection; The air flowing through the arcuate gap 74 follows the path indicated by the letter G, shown in FIG. 6.

Both of the apertures 50 and 52, may be spot welded to their respective intermediate spacer members, 64 and 72, as indicated in FIGS. 3, 4, 5 and 6, by an array of spot weld marks 69.

The cooling permitted by the apertures 50 and 52, is caused by the forced convective cooling close to the combustor basket wall 47.

Though the invention has been described with a certain degree of particularity, numerous changes may be made in the invention without departing from the scope and spirit thereof. For example, several gaps could be disposed at several locations within the spacer member, as suggested by the above description or an alternate inlet embodiment may be used to pull the air into the combustor, in addition to the use of spacer members having an arrangement of gaps therein for improved flow of cooling fluid therethrough.

I claim:

1. A combustor for a gas turbine comprising:

a generally cylindrical combustor basket;

a fuel spray nozzle disposed generally at the upstream end of said generally cylindrical combustor basket; an ignitor member disposed near the upstream end of said generally cylindrical combustor basket; annular arrays of air inlets comprising:

annular arrays of air scoops disposed in said generally cylindrical combustor basket;

annular arrays of air orifices disposed in said generally cylindrical combustor basket;

said air scoops being comprised of generally tubular members extending inwardly through holes in said combustor basket, said tubular members each having a generally annular flange on its radially outermost portion, said generally annular flange being disposed generally radially outwardly of the wall of said generally cylindrical combustor basket;

an intermediate generally annular spacer member disposed between said generally annular flange and said combustor basket;

said generally annular flange and said intermediate generally annular spacer member being fixedly at tached to each other and said combustor basket;

said intermediate generally annular spacer member between said generally annular flange and said combustor basket having at least one arcuate gap disposed therein;

said air orifices being comprised of;

a disc member having an air passage hole there through, said hole in said disc member being disposed generally radially outwardly of its respective adjacent hole in said combustor basket;

a second intermediate generally annular spacer member disposed between each of said disc members and said combustor basket;

said disc members and said second intermediate annular spacer members being fixedly attached to each other and said combustor basket;

said second intermediate generally annular spacer member between said disc member and said combustor basket having at least one generally arcuate gap disposed therein.

2. A combustor for a gas turbine as recited in claim 1, wherein said arcuate gap in said intermediate spacer member radially inwardly of said generally annular flange is disposed on the generally downstream side of said intermediate spacer member.

3. A combustor for a gas turbine as recited in claim 1, wherein said arcuate gap in said second intermediate spacer member radially inwardly of said disc member, is disposed on the generally downstream side of said second intermediate spacer member.

4. A combustor for a gas turbine as recited in claim 1, wherein said air scoops and said air orifices are fixedly attached to said intermediate spacer members and said combustor basket by spot welding.

5. A combustor for a gas turbine as recited in claim 1, wherein said spacer member for said air inlets have a plurality of arcuate gaps therein for the passage of 

1. A combustor for a gas turbine comprising: a generally cylindrical combustor basket; a fuel spray nozzle disposed generally at the upstream end of said generally cylindrical combustor basket; an ignitor member disposed near the upstream end of said generally cylindrical combustor basket; annular arrays of air inlets comprising: annular arrays of air scoops disposed in said generally cylindrical combustor basket; annular arrays of air orifices disposed in said generally cylindrical combustor basket; said air scoops being comprised of generally tubular members extending inwardly through holes in said combustor basket, said tubular members each having a generally annular flange on its radially outermost portion, said generally annular flange being disposed generally radially outwardly of the wall of said generally cylindrical combustor basket; an intermediate generally annular spacer member disposed between said generally annular flange and said combustor basket; said generally annular flange and said intermediate generally annular spacer member being fixedly attached to each other and said combustor basket; said intermediate generally annular spacer member between said generally annular flange and said combustor basket having at least one arcuate gap disposed therein; said air orifices being comprised of; a disc member having an air passage hole therethrough, said hole in said disc member being disposed generally radially outwardly of its respective adjacent hole in said combustor basket; a second intermediate generally annular spacer member disposed between each of said disc members and said combustor basket; said disc members and said second intermediate annular spacer members being fixedly attached to each other and said combustor basket; said second intermediate generally annular spacer member between said disc member and said combustor basket having at least one generally arcuate gap disposed therein.
 2. A combustor for a gas turbine as recited in claim 1, wherein said arcuate gap in said intermediate spacer member radially inwardly of said generally annular flange is disposed on the generally downstream side of said intermediate spacer member.
 3. A combustor for a gas turbine as recited in claim 1, wherein said arcuate gap in said second intermediate spacer member radially inwardly of said disc member, is disposed on the generally downstream side of said second intermediate spacer member.
 4. A combustor for a gas turbine as recited in claim 1, wherein said air scoops and said air orifices are fixedly attached to said intermediate spacer members and said combustor basket by spot welding.
 5. A combustor for a gas turbine as recited in claim 1, wherein said spacer member for said air inlets have a plurality of arcuate gaps therein for the passage of cooling fluid therethrough. 